Resistance unit.



No. 845,225. PATENTED PEB. 26, 1907. R. FLEMING.

RESISTANCE UNIT.

APPLICATION FILED JAN. 26, 1906.

Wit/765565; fine/750W W Arty as clay, cement, &c. and likewise to attach RICHARD FLEMING, OF LYNN,-

MASSACHUSETTS, ASSIGNOR TO GENERAL,

1 ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

neelsranca nan-r.

fiipecification of Letters Patent.

Patented Feb. 26, 190?.

Application filed January Z6,1906. Serial No. 298.003.

To all whom it may concern:

Be it known that I, RICHARD FLnMrNe, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful linprovements in Resistance Units, of which the following is a specification.

This invention relates .to improvements in resistance ,devices for electric circuits, and has for its object the provision of a device of this character which will have a broad application in connection with electric circuits wherever it is desired to provide a cheap,

safe, and eificient insulation which wil stand a high temperature, in addition to sudden changes of temperature, while at the same time retaining its insulating properties.

In the art to which this invention relates it has been common to embed the conductor in heat-refractory insulating materialssuch the conductor to a base, which may be either of conducting or insulating material, by means of some heat-refractory insulating material, such as enamel, the conductor being applied to the enamel While the latter is in a plastic condition; the whole being after Ward baked at a high temperature. devices of this character are open to many objections. In the first place, the fusing-point of the enamel is exceedingly high, and to embed the conductor in this enamel, and thus r se it to so high a temperature, is oftentimes very injurious. Moreover, thechanges in temperature and the expansion and contraction of the conductor caused thereby crack the enamel. Furthermore, when the conductor is embedded in the enamel it is diili cult to repair an injury either to the conductor or to the insulation-itself.

In carrying out my invent-ion it is my object to provide a resistance device which may be used either where heat is the object desired, as in the case of-el'ectric heaters, or where heating is only incidental, as in the case of rheostats. l likewise use the enamel base; but instead of embedding the conductor in the enamel I provide supporting'or attaching means which is heat-refractory and an insulator which 1 embed in the enamel and then attach the conductor to the sup porting device. I find that ave 'ient arrangement is to take a resistance fab- CORVEII- ric which is composed of insulating elements having a resistance-conductor running back and forth therethrough and attach the insulatin element to the enamel. This insulating e ement may be flexible-as, for instance, asbestos cords havin a conductor woven back and forth throug 1 the cordsor it may be a web of material composed of insulating buttons; with a conductor binding them togather. in either case the conductor not being embedded is free to expand and contract independently of the enamel. My invention therefore comprises a resistance device in which this conductor is enameled to a base through the medium of a supporting or attaching means, the conductor itself not being attached to the enamel.

it do not, of course, limit my invention to the use of enamel; but any material of this character which will stand the temperature to which it will be subjected will come within the" scope of my invention, and it is not, moreover,. essential that the material be an insulator, so long as the attaching means serves to insulate the conductor from the base. A

in the drawings, l i ure 1 is a plan view of resistance device em' odying my invention. Fig. 2 is a partial transverse section thereof somewhatenlarged. Fig. 3, is a plan view of another form of my invention, and Fig. 4 is an elevation of the same. n "U Referring to the drawings, igs. l and 2,

it) is a supporting-base andmay be of any desired'materialsuch, for instance, as castiron-or it may be of insulating material, such as slate, soapstone, or porcelain. Mounted upon this base is a flexible resist ance fabric composed of cords 11, ofsome heat-resisting material, such as asbestos. A resistanceconductor 12 traverses back and "forth alternately over and under the cords, forming the woof of the fabric. if desired, woof-threads 13, of asbestos,-may also be supplied, as shown in patent to Heath, No. 557,385. This fabric is attached to the base 10 bymeans oia material 14;, in which the cords ii are embedded. This material may he commercial enamel or an material which will stand a high temperature and which will securely fasten the cords thereto, it also being essential that the material shall assume a soft or plastic condition and will harden under heat. The conductor 12 is not embedded in the enamel, and although it is securely fixed thereby it is still free to respond to changes in temperature independently of the enamel.

are strong and will stand Without danger a temperature equal to the fusing-point of the enamel.

in which the means for supporting the conductor consists not of yielding elements, but of rigid insulating-buttons 15. These buttons and the conductor running therethrough form a fabric such as is described in the application of Harry E. Heath, Serial No. 236,457, filed December 12, 1904. These buttons are preferably made with slots 16, so that in case one is destroyed it' can be easily replaced. These buttons are likewise embedded in the enamel, as shown, while the conductor is entirely free of the enamel. The buttons and conductor may be applied to the base in the form of a fabric, or the buttons may be enameled to the base and the wire then threaded back and forth through I the buttons.

Various modifications and changes will suggest themselves to those skilled in the art which will be within the spirit of my invention, and it should be understood that I do not limit my invention to the precise arrangement of elements nor to the material used except in so far as it is limited by the scope of the claims annexed to and forming a part of this application.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The combination with a base, of a flexible resistance fabric enameled-thereto, the resisting element being unembedded whereby it is free to move independently of the enamel.

2. A resistance unit comprising an enameled base, insulating supporting means em-, bedded therein, and a resistance-conductor The cords 11 form a yielding support for the conductor and at the same time running back and forth through said support above the surface of the enamel,

3. A resistance unit comprising an enameled base, -a resistance-conductor running J back and forth above the surface of the same, and means embedded in said enamel for supporting said conductor.

4. A resistance unit comprisin a base,

, conductor-attaching devices ename ed there- In Figs. 3 and 4 I have shown another form to, and a resistance-conductor running back and forth above the surface of the enamel in engagement with the attaching devices.

5. A resistance device comprising a base, a coating of vitreous material thereon, a resistance-conductor running back and forth above the surface thereof, and insulating supporting means embedded in said material for supporting said conductor.

6. A resistance device comprising a base, a resistance-conductor running back and forth across the same, supporting means for said conductor, and a vitreous enamel embedding the supporting means and leaving the conductor unembedded whereby it is free to move independently of the base.

7. A resistance device comprising a base having a coating of refractory material thereon, a series of heat-resistant insulating attaching devices embedded therein, and a resistance-conductor running back and. forth above the surface of the material in engagement with the attaching devices.

8. A resistance unit comprising a base having a coating of enamel thereon, a series of heat-refractory insulating attaching de vices embedded therein, and a resistanceconductor running back and forth above the surface of the enamel and engaging the successive devices on their oppositesides.

In witness whereof I have hereunto set my hand this 25th day of January, 1906.

RICHARD FLEMING.

Witnesses: l

BENJAMIN B. HULL, HELEN ORFORD. 

